Feasibility Research of Determined Oxygen Permeability of Finished Soft Contact Lens / 中国医疗器械杂志

<p><b>OBJECTIVE</b>A method for determined oxygen permeability (Dk) of finished soft contact lens.</p><p><b>METHODS</b>Oxygen permeability(Dk) of 10 group finished soft contact lens was determined by polarographic method, and the values were linearly calibrated using the measured and established Dk values of the specified reference materials.</p><p><b>RESULTS</b>Only one Dk value fell outside of the requirement of GB 11417.3-2012 tolerance for Dk (± 20%).</p><p><b>CONCLUSION</b>It is great practicability when determined the oxygen permeability (Dk) of finished soft contact lens by polarographic method which were linearly calibrated using the measured and established Dk values of the specified equal thickness reference materials without the measured lens customized 4 different thickness.</p>

The effect of urea on the corrosion behavior of different dental alloys.

Objective: Intraoral corrosion of dental alloys has biological, functional, and esthetic consequences. Since it is well known that the salivary urea concentrations undergo changes with various diseases, the present study was undertaken to determine the effect of salivary urea concentrations on the corrosion behavior of commonly used dental casting alloys. Materials and Methods: Three casting alloys were subjected to polarization scans in synthetic saliva with three different urea concentrations. Results: Cyclic polarization clearly showed that urea levels above 20 mg/100 ml decreased corrosion current densities, increased the corrosion potentials and, at much higher urea levels, the breakdown potentials. Conclusion: The data indicate that elevated urea levels reduced the corrosion susceptibility of all alloys, possibly through adsorption of organics onto the metal surface. This study indicates that corrosion testing performed in sterile saline or synthetic saliva without organic components could be misleading.

Determination of free cisplatin in medium by differential pulse polarography after ultrasound and cisplatin treatment of a cancer cell culture.

The in vitro study was carried out for detection of the cisplatin in free form and in culture medium, depending on various conditions of sonodynamic human ovarian cancer cells A2780 treatment by differential pulse polarography (DPP). For sonodynamic treatment, we used cisplatin alone and combined cisplatin/ultrasound treatments. The ultrasound exposure intensity of 1.0 and 2.0 W∙cm-2 in far field for incubation periods 1, 24 and 48 h was used. The parameters of DPP measurements were - 1 s drop time, 5 mV.s-1 voltage scan rate, 50 mV modulation amplitude and negative scanning direction; platinum wire served as counter electrode and Ag|AgCl|3 M KCl as reference electrode. The results showed the dependence of free platinum quantities in culture medium on incubation time and treatment protocol. We found difference in concentration of free cisplatin between conventional application of cisplatin and sonodynamic treatment. The sonodynamic combined treatment of cisplatin and ultrasound field showed a higher cisplatin content in the culture medium than cisplatin treatment alone; a difference of 20% was observed for incubation time 48 h. The results also showed the influence of a time sequence of ultrasound and cytostatics in the sonodynamic treatment. The highest amount of free cisplatin in the solution was found for primary application of cisplatin and the subsequent ultrasound exposure. The quantity of free cisplatin increased with time, namely for time intervals 1-24 h. There was no difference between the DPP signal of cisplatin in reaction mixture containing cells in small quantities and micro-filtered mixture without cells. Thus, the DPP method is suitable for the detection and quantification of free cisplatin in the culture medium of cell suspension. Ultrasound field can be important factor during cytostatic therapy.

A non-invasive glucose measurement method based on orthogonal twin-polarized light and its pilot experimental investigation / 生物医学工程学杂志

In order to overcome the existing shortcomings of the non-invasive blood glucose polarized light measurement methods of optical heterodyne detection and direct detection, we present in this paper a new orthogonal twin-polarized light (OTPL) non-invasive blood glucose measurement method, which converts the micro-angle rotated by an optical active substance such as glucose to the energy difference of OTPL, amplifies the signals by the high-sensitivity lock-in amplifier made of relevant principle, controls Faraday coil current to compensate the changes in deflection angle caused by blood glucose, and makes use of the linear relationship between blood glucose concentration and Faraday coil current to calculate blood glucose concentration. In our comparative experiment using the data measured by LX-20 automatic biochemical analyzer as a standard, a 0.9777 correlation coefficient is obtained in glucose concentration experiment, and a 0.952 in serum experiment. The result shows that this method has higher detection sensitivity and accuracy and lays a foundation for the development of practical new type of non-invasive blood glucose tester for diabetic patients.

The electrochemical properties of four dental casting suprastructure alloys coupled with titanium implants

OBJECTIVES: As the choice of suprastructure alloy to be combined with titanium for the oral cavity is still a much debated issue, the aim of this study was to investigate the electrochemical interaction of the suprastructure/implant couples under the determined experiment conditions. MATERIAL AND METHODS: The potentiodynamic polarization curves and open-circuit potentials (OCP) of four UCLA type suprastructures coupled with straight Swiss Plus implant fixtures were taken in Afnor type artificial saliva solution at 37°C. The concentration of ions leached into artificial saliva solutions was estimated with ICP-MS. SEM images of the margins of suprastructure/implant couples were obtained before and after the electrochemical tests. RESULTS: The OCP value of titanium became passive at the most negative potential. The lowest difference between the initial and constant OCP value was exhibited by the Au based suprastructure. Suprastructures made greater contributions to the potentiodynamic polarization curves of the implant/suprastructure couples. According to the ICP-MS results, Pd based and Au based couples dissolved less than Co-Ni based and Co-Cr based couples. CONCLUSIONS: Within the conditions this study, it may be concluded that the titanium implant forms a stable passive oxide layer in artificial saliva exposed to open air and does not affect the corrosion properties of the suprastructures. Pd based and Au based couples have been found to be more corrosion-resistant than base alloy couples.

Chemometric determination of rabeprazole sodium in presence of its acid induced degradation products using spectrophotometry, polarography and anodic voltammetry at a glassy carbon electrode

Chemometric stability indicating methods are presented for the determination of rabeprazole sodium in presence of its acid induced degradation products using spectrophotometry, differential pulse polarography and differential pulse anodic voltammetry at a glassy carbon electrode. The applied chemometric techniques are multivariate ones including classical least squares [CLS], principal component regression [PCR] and partial least squares [PLS]. A difference spectrophotometric [?A] method has also been applied. To develop the multivariate calibrations, a training set was used, consisting of 20 mixture solutions of rabeprazole sodium and its degradation products. These mixtures show percentage degradation ranging from 0.5-65%, 0.5-95% and 0.6- 75% for the spectrophotometric, polarographic and anodic voltammetric calibrations, respectively. The UV absorbances were recorded in 0.1 M NaOH within the wavelength range 220-340 nm at 2 nm intervals. The polarograms and anodic voltammograms were recorded in Britton- Robinson buffer [pH 8.0] within the potential range -500 to -1508 and 400 to 1192 mV at 6 mV intervals with a pulse amplitude of -100 and 50 mV, sweep rate of 15 and 10 mV s-1 and pulse interval of 0.4 and 0.6 s for the polarographic and anodic voltammetric methods, respectively. All the studied methods have been validated and successfully applied to the determination of rabeprazole sodium in tablet dosage form. The results were statistically compared to those obtained using a published HPLC method. No significant difference has been found

Inclusion of coenzyme Q10 with beta-cyclodextrin studied by polarography / 药学学报

<p><b>AIM</b>To investigate the inclusion of coenzyme Q10 with beta-cyclodextrin (beta-CD).</p><p><b>METHODS</b>The inclusion of the electroactive guest molecule coenzyme Q10 with the host molecule beta-CD was studied by the polarography. The change of the reduction peak current of the inclusion complex with time and the change of the peak potential of the inclusion complex with beta-CD concentration were examined. In order to study the photostability, the change of the reduction peak current of both coenzyme Q10 and coenzyme Q10-beta-CD inclusion complex with time were also examined under light, separately.</p><p><b>RESULTS</b>In 0.1 mol x L(-1) HAc/NaAc (pH 4.7) buffer-ethanol/water (60:40) medium, coenzyme Q10 was included with p-CD to form an 1:1 inclusion complex. The formation constant Kf was 1.26 x 10(4) L x mol(-1) the apparent formation rate constant was 6.64 x 10(-2) min(-1). The photodegradation apparent rate constant of coenzyme Q10 as 7.77 x 10(-3) min(-1) and that of the coenzyme Q10-beta-CD inclusion complex was 3.38 x 10(-3) min(-1).</p><p><b>CONCLUSION</b>The inclusion of coenzyme Q10 with beta-CD took place. The stability of coenzyme Q10 to lights was improved in a certain degree due to the formation of the inclusion complex.</p>

Polarographic behavior and determination of glimepiride / 药学学报

<p><b>AIM</b>To establish a polarographic method of parallel catalytic hydrogen wave for determination of glimepiride.</p><p><b>METHODS</b>The catalytic wave of glimepiride in the presence of K2S2O8 was used to improve the analytical sensitivity. The rapid determination of glimepiride was done by linear single sweep polarography.</p><p><b>RESULTS</b>The catalytic hydrogen wave of glimepiride was measured at ca. -1.36 (vs SCE) in 0.09 mol x L(-1) Na2B4O7-KH2PO4 (pH 6.24 +/- 0.1) supporting electrolyte. When 1.0 x 10(-2) mol x L(-1) K2S2O8 was present, the current increased by 25 times, and the peak potentioal was unchanged, producing a more sensitive parallel catalytic hydrogen wave. The peak current of the parallel catalytic hydrogen wave was rectilinear to the glimepiride concentration in the range 1.0 x 10(-7) - 4.2 x 10(-5) mol x L(-1) (r = 0.9990, n = 9). The detection limit was 5.0 x 10(-8) mol x L(-1).</p><p><b>CONCLUSION</b>The proposed method could be applied to the determination of glimepiride in pharmaceuticals without preliminary separation.</p>

Parallel catalytic hydrogen wave of acetylspiramycin caused by dissolved oxygen and its application / 药学学报

<p><b>AIM</b>To propose a novel polarographic method for the determination of acetylspiramycin (ASPM) is proposed.</p><p><b>METHODS</b>In 0.1 mol x L(-1) NH4Cl-NH3 x H2O (pH 8.9) buffer containing dissolved oxygen, ASPM yielded a sensitive parallel catalytic hydrogen wave with the peak potential of -1.63 V (vs SCE) by single sweep polarography.</p><p><b>RESULTS</b>The 2nd order derivative peak currents (i(p)") of the parallel catalytic hydrogen waves of ASPM showed a linear relationship with its concentrations in the range from 1.74 x 10(-3) microg x mL(-1) to 3.84 microg x mL(-1) (r = 0.9979, n=13). Its detection limit was 5.80 x l0(-4) microg x mL(-1) (3sigma) and RSD (n=13) was 1.24% at the concentration level of 0.871 microg x mL(-1).</p><p><b>CONCLUSION</b>The proposed method could be applied to the determination of ASPM in ASPM tablets.</p>

Polarograhic adsorptive wave of protein hydrolysate in Pb2+ and sodium hydroxide solution and its application / 药学学报

<p><b>AIM</b>To propose a new simple and sensitive voltammetric method for determination of proteins.</p><p><b>METHODS</b>Protein with sulfhydryl or disulfide bond in 0.5 mol x L(-1) NaOH, 1.5 x 10(-4) mol x L(-1) Pb2+ and 0.02% tetrabutylammonium iodide was heated in boiling water for 5 minutes. The reactive product gave a well defined reductive adsorption wave at -0.66 V (vs SCE) by means of single sweep polarography, and the height of derivative wave was proportional to the concentration of proteins.</p><p><b>RESULTS</b>The peak height was linearly proportional to bovine serum albumin (BSA) or human serum albumin (HSA) concentration in range of 7.5 x 10(-10) -3.0 x 10(-7) mol x L(-1) (r(BSA) = 0.9995, and r(HSA) = 0.9990). The detection limit of BSA or HSA was 3.0 x 10(-10) mol x L(-1). For lysozyme (Lyso), the concentration range was from 1.4 x 10(-8) to 1.3 x 10(-6) mol x L(-10 (r(Lyso) = 0.9997) and the detection limit was 7.0 x 10(-9) mol x L(-1).</p><p><b>CONCLUSION</b>The method is simple, rapid, sensitive and applicable to the assay of diluted human serum albumin samples.</p>

Polarographic catalytic wave of clarithromycin and its applications / 药学学报

<p><b>AIM</b>To develop a new method for the determination of clarithromycin.</p><p><b>METHODS</b>The catalytic wave of clarithromycin in the presence of K2S2O8 was used for improving the analytical sensitivity. The rapid determination of clarithromycin has been carried out by linear single sweep polarography.</p><p><b>RESULTS</b>The reduction wave of clarithromycin appeared at ca. -0.79 V (vs SCE) in 0.24 mol x L(-1) KH2PO4-Na2HPO4 (pH 6.81) supporting electrolyte, which was ascribed to the reduction of carbonyl group on C-9 position. In the presence of 0.01 mol x L(-1) K2S2O8, the reduction wave was catalyzed to produce a parallel catalytic wave. The peak current of the catalytic wave was ca. Twenty times higher than that of the corresponding reduction wave. Based on the catalytic wave, a new method for the determination of clarithromycin has been proposed. The peak current of the catalytic wave was rectilinear to clarithromycin concentration in the range of 4.0 x 10(-7)-5.0 x 10(-5) mol x L(-1). The detection limit was 2.0 x 10(-7) mol x L(-1).</p><p><b>CONCLUSION</b>The proposed method could be used for the direct determination of clarithromycin in pharmaceuticals and urine without preliminary separation.</p>

Odontologic use of copper/aluminum alloys: mitochondrial respiration as sensitive parameter of biocompatibility

Copper/aluminum alloys are largely utilized in odontological restorations because they are less expensive than gold or platinum. However, tarnishing and important corrosion in intrabuccal prostheses made with copper/aluminum alloys after 28 days of use have been reported. Several kinds of food and beverage may attack and corrode these alloys. Copper is an essential component of several important enzymes directly involved in mitochondrial respiratory metabolism. Aluminum, in contrast, is very toxic and, when absorbed, plasma values as small as 1.65 to 21.55 µg/dl can cause severe lesions to the nervous system, kidneys, and bone marrow. Because mitochondria are extremely sensitive to minimal variation of cellular physiology, the direct relationship between the mitocondrial respiratory chain and cell lesions has been used as a sensitive parameter to evaluate cellular aggression by external agents. This work consisted in the polarographic study of mitochondrial respiratory metabolism of livers and kidneys of rabbits with femoral implants of titanium or copper/aluminum alloy screws. The experimental results obtained did not show physiological modifications of hepatic or renal mitochondria isolated from animals of the three experimental groups, which indicate good biocompatibility of copper/aluminum alloys and suggest their odontological use

Determination of irisquinone by single sweep oscillopolarography / 药学学报

<p><b>AIM</b>To propose a polarographic method for the determination of irisquinone.</p><p><b>METHODS</b>A reduction wave of irisquinone was recorded by single sweep oscillopolarography.</p><p><b>RESULTS</b>In 8.0 x 10(-3) mol.L-1 Na2B4O7-1.6 x 10(-2) mol.L-1 KH2PO4 (pH 7.7) supporting electrolyte, a redution wave of irisquinone with peak potential -1.23 V (vs SCE) achieved high sensitivity. The 2nd-order derivative peak current of the reduction wave was proportional to irisquinone concentration in the range of 1.5 x 10(-7)-5.2 x 10(-6) mol.L-1 (gamma = 0.9992, n = 9). The detection limit was 6.0 x 10(-8) mol.L-1. Relative standard deviation (RSD) was 0.87% by performing 13 independent measurements on 2.0 x 10(-6) mol.L-1 irisquinone.</p><p><b>CONCLUSION</b>The proposed method was sensitive, simple, rapid, and can be applied to the determination of irisquinone in raw medicine and capsule.</p>

Polarographic method for the determination of lansoprazole in dosage form and spiked human urine

A simple, rapid and sensitive polarographic method is described for the determination of lansoprazole in a pure form, capsules and in urine. The proposed method is based on the measurement of the direct current [DC[t]] and the differential pulse polarographic [DPP] peak produced by lansoprazole in Britton-Robison buffer at pH 9, which give a well-defined cathodic wave. The current-concentration relationship was found to be rectilinear over the range 2-20 micro.g/ml and 0.1-2 [micro g/ml, in the direct current DCt and in the differential pulse polarography DPP modes, respectively, with a minimum detectability [S/N = 2] of 0.01 micro,g/ml [2.7 x 10[-8] M]. The number of electrons involved in the reduction process was established through comparison of the wave height of lansoprazole with that obtained for an equimolar solution of omeprazole. The proposed method was successfully applied to the determination of lansoprazole in commercial capsules adopting the DCt techniques. The results obtained were in accordance with those found using the reported spectroscopic method. The percentage recovery was 100.8 +/- 1.4%. Furthermore, the proposed method was applied for the determination of lansoprazole in urine adopting the DPP technique. The percentage recovery was 99.15 +/- 1.22%

Padronizaçäo do método polarográfico no tumor de Walker em ratos Wistar / Standardization of polarography in Walker tumor inoculated in Wistar rats

Estudo polarográfico foi realizado em 15 ratos Wistar inoculados com tumor de Walker 256, implantando-se eletrodos de platina no tumor e no músculo, com o objetivo de padronizaçäo da polarografia no tumor de Walker 256. Os níveis de oxigênio foram sempre menores no tumor do que no músculo, tanto em condiçöes basais como após a oxigenaçäo. A resposta à oxigenaçäo foi mais lenta no tumor do que no músculo

Analysis of Heavy Metals in 201TlTlCl Injection Using Polarography / 대한핵의학회잡지

PURPOSE: Thallous-201 chloride produced at Korea Cancer Center Hospital(KCCH) is used in detecting cardiovascular disease and cancer. Thallium impurity can cause emesis, catharsis and nausea, so the presence of thallium and other metal impurities should be determined. According to USP and KP, their amounts must be less than 2 ppm in thallium and 5 ppm in total. In this study, the detection method of trace amounts of metal impurities in [201Tl]TlCl injection with polarography was optimized without environmental contamination. MATERALS AND METHODS: For the detection of metal impurities, Osteryoung Square Wave Stripping Voltammetry method was used in Bio-Analytical System (BAS) 50W polarograph. The voltammetry was composed of Dropping Mercury Electrode (DME) as a working electrode, Ag/AgCl as a reference electrode and Pt wire as a counter electrode. Square wave stripping method, which makes use of formation and deformation of amalgam, was adopted to determine the metal impurities, and pH 7 phosphate buffer was used as supporting electrolyte. RESULTS: T1, Cu and Pb in thallous-201 chloride solution were detected by scanning from 300 mV to -800 mV. Calibration curves were made by using TlNO3, CuSO4 and Pb(NO3)2 as standard solutions. Tl was confirmed at -450 mV peak potential and Cu at -50 mV. Less than 2 ppm of Tl and Cu was detected and Pb was not detected in KCCH-produced thallous-201 chloride injection. CONCLUSION: Detection limit of thallium and copper is approximately 50 ppb with this method. As a result of this experiment, thallium and other metal impurities in thallous-201 chloride injection, produced at Korea Cancer Center Hospital, are in the regulation of USP and KP. Polarograph could be applied for the determination of metal impurities in the quality control of radiopharmaceuticals conveniently without environmental contamination.

Role of bio-metal Fe(III) in anticancer effect of dacarbazine.

Physicochemical, Microbial and Pharmacological studies on Fe(III)-Dacarbazine complex have been done in solid and aqueous phase. On the basis of elemental analysis, polarographic studies, amperometric titrations and IR spectral studies the probable formula for the complex has been worked out to be 1:1, Fe(III)-Dacarbazine. The metal ligand interaction has been studied using polarographic method at 25 +/- 1 degrees C and at ionic strength of mu = 1.0 (KCl). Microbial studies on the complex was done against various pathogenic bacteria viz. Pseudomonas mangiferae, Staphylococcus aureus, Salmonella typhi and Vibrio cholarae and fungi i.e. Trichothecium and Chrysosporium sp. using Raper's method. Mouse sarcoma cell line 180 and Balb/C mice were used for the anticancer screening of solid complex in vitro and in vivo respectively. The observed polarographic data, on lingane treatment revealed the formation of single (1:1) (M:L) complex with Fe(III) and dacarbazine ligands. The results of amperometric titrations of Fe(III) with dacarbazine in IM KCl supporting electrolyte pH 7.0 +/- 0.1 supported the above findings the IR data speaks of the complex formation between the metal and the dacarbazine ligand through the two nitrogen one each of primary amide and trizo groups. The results of microbial and pharmacological studies with the M:Drug complex revealed that the anticancer activity of the drug metal complex is nearly doubled as compared to the pure drug. As such Fe(III) dacarbazine complex may be recommended to the therapeutic experts for its possible use as more potent anticancer drug.

Electrochemical behaviour of some arylidene derivatives of carbohydrazide at mercury electrode in aqueous ethanolic buffer solutions

The electrochemical behavior of some arylidene derivatives of carbohydrazides was investigated by dc-polarography, de-polarography, cyclic voltammetry, and controlled potential coulometry techniques, at a mercury electrode in 50% ethanolic Britton-Robinson buffer solutions of pH 2-10. In acidic media [pH <4], the reduction occurs along a single irreversible 8-electron wave corresponding to the cleavage of the 2 N-N bonds and saturation of the 2 C=N centers, while at 6 /7] the total limiting current decreases on increasing the pH, this decrease is accompanied with the formation of a polarographic minimum till the wave disappears completely at pH's >10. The kinetic parameters, nature of the waves, the effect of pH on the limiting current and half-wave potentials as well as the reduction mechanism are discussed

Determinaçäo de pesticidas por técnicas eletroanalíticas / Pesticides determination by electroanalytical techniques

Apresenta revisao sobre a aplicaçao de técnicas eletroanalíticas na análise e determinaçao de pesticidas em vários meios, como águas naturais, frutas, cereais e solos, entre outros. O baixo custo das análises, a facilidade de manipulaçao das amostras, o curto tempo de realizaçao das medidas e a sensibilidade a interferentes sao as principais vantagens desta aplicaçao. As técnicas eletroanalíticas mais utilizadas sao a polarografia de corrente direta (DC), a polarografia de pulso diferencial e a voltametria adsortiva, em cerca de 60 ingredientes ativos de pesticidas das mais diferentes classes, ou seja, triazinas, organoclorados, organofosforados, carbamatos, compostos nitros e outros.